MESOSCALE DISCUSSION 1877
   NWS STORM PREDICTION CENTER NORMAN OK
   0810 PM CDT SAT AUG 06 2011
   
   AREAS AFFECTED...PORTIONS ERN NEB...IA...EXTREME NERN KS...NWRN AND
   EXTREME N-CENTRAL MO.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 732...
   
   VALID 070110Z - 070315Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 732
   CONTINUES.
   
   CONTINUE WW...WITH SOME CLEARING POSSIBLE BEHIND OUTFLOW BOUNDARIES
   PRODUCED BY WRN TSTMS.  ADDITIONAL COUNTIES HAVE BEEN ADDED TO SERN
   NEB PORTIONS WW PER COORD W/OAX.  ANOTHER WW MAY BE REQUIRED FARTHER
   E OR SE DURING NEXT 2-3 HOURS ALSO.
   
   SFC MESOANALYSIS SHOWS COLD FRONT MOVING SEWD ACROSS NWRN IA AND
   CENTRAL NEB...MOVING SEWD ABOUT 10-15 KT.  MOIST AXIS WAS DRAWN FROM
   STL AREA NWWD OVER NRN MO TO EXTREME SWRN IA...WITH BROAD SWATH OF
   70S SFC DEW POINTS ON EITHER SIDE.  TSTMS OVER WRN IA AND SERN NEB
   ARE IS INCREASING IN COVERAGE...WITH SOME RISK FOR AGGREGATION INTO
   QLCS AND MOVE EWD TO ESEWD ACROSS PORTIONS IA AND NRN MO.  THIS
   POSSIBILITY IS SUPPORTED BY BLEND OF MODIFIED OAX RAOBS AND RUC FCST
   SOUNDINGS DOWNSHEAR...WHICH INDICATE FAVORABLE BUOYANCY AND SHEAR
   PERSISTING FOR MUCH OF EVENING AND CONSIDERABLE DISTANCE EWD.  SFC
   DEW POINTS COMMONLY IN 70S F WILL ENSURE ONLY SLOW NOCTURNAL
   DIABATIC COOLING/DESTABILIZATION OF FOREGOING BOUNDARY LAYER...AND
   NEARLY SFC-BASED EFFECTIVE PARCELS FOR SEVERAL MORE HOURS WITH
   MLCAPE RANGING FROM 2000-4000 J/KG.  ALTHOUGH LOW-LEVEL FLOW IS WEAK
   AND SHOULD REMAIN SO...GREAT DEPTH OF CAPE LAYER RESULTS IN
   EFFECTIVE SHEAR BEING SAMPLED INTO STRONGER UPPER WINDS...IN TURN
   YIELDING MAGNITUDES 40-50 KT.  NEARLY UNIDIRECTIONAL/ZONAL LAYER OF
   FLOW ALSO YIELDS MEAN WIND/SHEAR VECTORS ALIGNED NEARLY ORTHOGONALLY
   WITH RESPECT TO POTENTIAL QLCS ORIENTATION.  FARTHER W..CLUSTER OF
   STG-SVR TSTMS W OFK...INCLUDING LEFT SPLITS...WILL MOVE THROUGH
   FAVORABLE AIR MASS BEFORE ANY INTERACTION WITH OUTFLOW FROM EITHER
   SERN NEB OR WRN IA CONVECTION...ALSO AMIDST 40-50 KT EFFECTIVE SHEAR
   MAGNITUDES.
   
   ..EDWARDS.. 08/07/2011
   
   
   ATTN...WFO...DVN...DMX...EAX...FSD...OAX...TOP...GID...LBF...
   
   LAT...LON   41779833 42279777 42639410 42519223 42179183 40859200
               40439233 39869353 39769480 39949570 40479753 41779833